Wow, some great information here. Thanks for taking the time!
On Feb 7, 6:38 pm, Christoph Studer <chstu...@gmail.com> wrote: > Android uses a very proactive power management approach. Basically, > the policy is to go to sleep if not told otherwise. > > The way to signal to the system that it should stay awake are > wakelocks. As soon as there's at least one app holding a wakelock, the > system won't go to sleep and all the running processes can do their > work (even those that are not holding a wakelock at that moment). > > Any application with the according permission can acquire a wakelock > and thus prevent the system from sleeping. There are several "wakelock > levels", you can read all the details > here:http://code.google.com/android/reference/android/os/PowerManager.html > > In your case, as a background service, you probably want to hold a > PARTIAL_WAKE_LOCK which will keep the CPU running as long as it's > acquired. > > Please be very careful with using the wakelock, as this affects > battery life a lot and it is hard for users to determine which > application is causing the drainage and uninstall it. For every > acquire(), make sure you have a matching release() call that is > guaranteed to be executed* and only hold the lock for the minimal > amount of time. > > Also ask yourself whether it's crucial that your service is preventing > the system to go to sleep or whether it would be enough to do work > only when the system is awake anyway (e.g. because the user is > interacting with the phone). > > The AlarmManager can be used to get an intent delivered to you at a > certain time, regardless of the sleep-state of the system. The > AlarmManager will wake the system up if necessary and hold a wakelock > until the intent has been delivered to you. > > As you should not do long-lasting work on the main thread of your > service (which is receiving the intent), you should spawn a thread and > manually acquire a wakelock. > > Sorry for the long post and I hope this information is helpful (and > accurate :-)). > > Christoph > > * One has to pay special attention to the control flow in the case of > exceptions. Make sure that a thrown exception won't prevent release() > from being called: > > void doSomeWork() throws SomeException { ... } > > void barWrong() { > try { > wakelock.acquire(); > doSomeWork(); > wakelock.release(); // <- Won't be called on exception > } catch (SomeException e) { > Log.w(...); > } > > } > > void barRight() { > try { > wakelock.acquire(); > doSomeWork(); > } catch (SomeException e) { > Log.w(...); > } finally { > wakelock.release(); > } > > } > > On Sat, Feb 7, 2009 at 11:19 PM, clarkbriancarl > > <clarkbrianc...@gmail.com> wrote: > > > Thanks for the reply. I've been reading and tweaking for over a week > > trying to figure this out. Thats a good idea to use the Alarm Manager. > > I think I will give that a try. I would still like to hear from a more > > experienced devloper or a google engineer if this is the way an > > Android service is supposed to behave. > > > On Feb 7, 3:29 pm, Greg White <debauchedsl...@gmail.com> wrote: > >> On Sat, Feb 7, 2009 at 11:50 AM, Brian <clarkbrianc...@gmail.com> wrote: > >> > While testing the service, I have come across something interesting. > > >> > My problem is that the service appears to sleep or pause for a few > >> > hours, run a short time, and then sleep for a few more hours, then run > >> > a short time, etc when the phone has become inactive. > > >> I'm interested to hear what others say. My experience mirrors yours. I > >> believe the phone is going to sleep and freezing the service. > > >> What I did was to use the AlarmManager to wake the service to do its work. > >> While it was working, I used a wake lock to keep the phone from sleeping. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
